Why do graphic shaders stop working in 3.2.4 update even when they are checked in prefences?

[Yuvi Robbiani]

I have gone back to 3.2.1 in which shaders work properly, so I don't believe it is an issue of my computer environment.

[Rolig Loon]

There are several well-documented conflicts between shaders and various features. 

For example, Version 3.0 Shadows Mode makes some objects / textures invisible

Or Black Screen when I enable Lighting and Shadows

Or "Basic Shaders" creating artifacts on alpha layer

The JIRA is full of reports on these conflicts.  The cure, for now, is to turn off shaders when they create a problem or, sometimes, to turn off OpenGL Virtual Buffer Objects (VBO).  Or go back to an earlier viewer or a TPV, as you have, or to wait until the bugs are fixed in a later release.

[Charolotte Caxton]

Shaders work in mine. I use an AMD card. If you are using an NVIDIA card you may have to tweek your settings. 

You may also need to change which drivers you are using.